Molecular electronics is a rapidly growing area of research that seeks to understand charge transport at the single molecule level. Such knowledge may create active nanostructures that extend computing, electronic memory, bio-chemical sensing, or energy harvesting beyond the limits of modern technologies. Although there are many challenges to the realization of practical molecular devices, the area holds great promise due to the richness of molecular properties and the complexity of inorganic, organic, and biological molecules that can be synthesized. In a broader scientific context, there is a desire to understand and harness the unique properties of matter on an atomic, or molecular, length scale.
According to the 2005 International Technology Roadmap for Semiconductors (ITRS), the gate length of state of the art transistors is expected to reach below 20 nm by 2015. These small dimensions are expected to create practical, as well as technical, limitations. For example, fabrication facility costs are projected to be $102 billion by 2015 (M. LaPedus, “Soaring Tool Costs to Delay 450 mm Fabs,” EE Times, Aug. 19, 2005). Moreover, management of the heat generated by multi-billion transistor chips is a major challenge. Thus, there is great interest in new concepts for future computing technologies. One of the areas of exploration is molecular electronics. Due to the vast possibilities of molecular synthesis and the atomic precision of molecule design, there is an interest in understanding the electrical properties of molecules for future nanoelectronic devices. Molecular devices may function as wires, switches, transistors, or sensors, for example.
The potential impacts of molecular electronics have ignited much interest in the measurement of electrical conduction through single molecules. The growing body of data has demonstrated the importance of chemical structure, electrode bonding chemistry, and electrode material on the observed molecular conductance. However, the understanding of electrode atomic structure and molecule-electrode bonding geometry in metal-molecule-metal tunnel junctions is lacking, and existing experimental techniques are not readily extended to address this problem. There is a need for new approaches to the study of electrode atomic structure, and the effects of structure on chemical bonding and charge transport at molecule-electrode interfaces. The present invention addresses these needs among others.